Method for analyzing a simulation of the execution of a quantum circuit

ABSTRACT

A method for analyzing a simulation of the execution of a quantum circuit comprises:
         a step of post-selecting (S 2 ) one or more particular values of one or more qubits at one or more steps of the simulation,   a step of retrieving (S 5 ), by an iterator ( 7 ), all or some of the quantum states of the quantum state vector(s) derived from the post-selection(s) of qubits,   a step of analyzing (S 6 ) the part of the simulation that corresponds to the post-selection(s) of qubits and to the quantum state vector(s) retrieved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of French Patent Application No.1873616 filed Dec. 20, 2018, the disclosure of which is hereinincorporated by reference in its entirety.

TECHNICAL FIELD

The invention falls within the field of methods for analyzingsimulations of the execution of a quantum circuit.

PRIOR ART

For such an analysis, it is known to repetitively perform a very largenumber of simulations, in order to obtain the values of all possiblequantum states.

It is also known to take intermediate measurements when simulating theexecution of the quantum circuit.

Technical Problem

These known solutions do not enable a good compromise between on the onehand simplifying the analysis of the execution of a quantum circuit andon the other hand completing the analysis performed.

SUMMARY OF THE INVENTION

The invention at least partially remedies the shortcomings of the priorart and improves the compromise mentioned above.

It involves being able to analyze the execution of a quantum circuit,particularly for the purposes of debugging that quantum circuit.

To do so, according to the invention, it will be beneficial both to beable to track the execution of that quantum circuit step-by-step andalso to extract in a simple and complete manner, one which istransparent to the analyst of the execution of that quantum circuit, allor some of the values of quantum state vectors for certain qubits ofparticular interest to that analyst, all in order to facilitate both thefocusing on the part of the execution of that quantum circuit consideredto be particularly interesting, while thereafter facilitating theextraction of data related to that part of the execution, the analysisof the execution of the quantum circuit while preserving thecompleteness of that analysis, i.e. without losing or sacrificing any orall of the quantum states considered interesting by the analyst, whichcould damage the completeness of the analysis and/or the running of theanalysis, potentially leading to a substantially less effectivedebugging of the execution of that quantum circuit.

To achieve this good compromise between substantially simplifying theanalysis of the execution of that quantum circuit and ensuring thecompleteness of that analysis, the invention proposes a particularcombination of a post-selection and a quantum iteration, both performedon a simulated execution rather than an actual execution.

The invention enables the analyst of the execution of the quantumcircuit to easily and effectively focus on the part of the execution ofthat quantum circuit that interests him or her, all while making theextraction of the interesting data obtained simpler or more transparentto him or her, hence providing a precise focus on what interests him orher, with a simpler way to extract only what interests him or her.

Likewise, the great simplification achieved through the use of a quantumiterator enables the user to carry out more numerous and more detailedpost-selection operations, without making the time spent or thedifficulty of analysis prohibitive.

DESCRIPTION OF THE INVENTION

A method is proposed for analyzing a simulation of the execution of aquantum circuit, comprising:

-   -   a step of post-selecting one or more particular values of one or        more qubits at one or more steps of the simulation,    -   a step of retrieving, by an iterator, all or some of the quantum        states of the quantum state vector(s) derived from the        post-selections of qubits    -   a step of analyzing the part of said simulation that corresponds        to the post-selection(s) of qubits and to the quantum state        vector(s) retrieved.

According to another aspect, a method is proposed for analyzing asimulation of the execution of a quantum circuit, comprising:

-   -   a step of post-selecting one or more particular values once the        measurement of one or more qubits is output,    -   a step of analyzing the part of said simulation that corresponds        to the post-selection(s) of qubits.

The features described in the following paragraphs may optionally beimplemented. They may be implemented independently of one another, or incombination with one another:

Preferably, the method comprises, between the post-selection step andthe analysis step:

-   -   a step of setting filtration that sets the value of one or more        quantum states of the quantum state vector(s) derived from the        post-selections of qubits. Thus, it may be beneficial both to be        able to track the execution of that quantum circuit step-by-step        and also to take measurements in various execution operations of        that quantum circuit without substantially disrupting the        execution of that quantum circuit, in order to facilitate the        analysis of the execution of that quantum circuit while        preserving the usefulness of that analysis, i.e. without any        disruptions in the execution of that quantum circuit,        particularly due to measurements, harming the usefulness of the        analysis of that quantum circuits execution, making it either        useless or less useful, thereby leading to a substantially less        effective debugging of the execution of that quantum circuit.

To achieve this good compromise between substantially simplifying theanalysis of the execution of that quantum circuit and that analysisbeing very useful, the invention proposes a particular combination of apost-selection and a setting filtration, both performed on a simulatedexecution rather than an actual execution.

The method therefore enables the analyst of the execution of the quantumcircuit to focus on a part of the execution of the quantum circuit thatinterests him or her and on the type of process for that execution part,increasing the options to debug the quantum circuit.

Preferably, the method comprises, between the post-selection step andthe analysis step, and before the step of retrieval:

-   -   the step of setting filtration that sets the value of one or        more quantum states of the quantum state vector(s) derived from        the post-selections of qubits.

This makes it possible to retrieve a quantum state vector that has beenfiltered beforehand. The analysis of the quantum state vector maythereby take place immediately after that quantum state vector has beenretrieved, without requiring any additional operations on that quantumstate vector.

Preferably, the method comprises:

-   -   a step of identifying each quantum state of said quantum state        vector(s) and a parameter representative of a probability that        is respectively associated with said each quantum state, located        between the step of post-selection and the step of retrieval,    -   the step of retrieval further comprising the retrieval of each        parameter representative of the probability respectively        associated with each quantum state.

The iterator therefore makes it possible to extract additionalinformation about the quantum state vector, in a simple and unsupervisedmanner. This makes it possible to further improve the completeness ofthe analysis of the execution.

Preferably, the step of post-selecting one or more particular values ofone or more qubits is carried out at the output of the measurement ofsaid qubit(s).

As the intermediate measurements or the final measurement are anintegral part of the execution, the post-selection step mayadvantageously be performed after one of those measurements. This makesit possible to analyze the simulation step-by-step.

Preferably, the step of post-selecting one or more particular values ofone or more qubits is carried out after a quantum gate operation on saidqubit(s).

Thus, knowing the sequence of operations during execution, thepost-selection step may be performed at any time during execution. Thisenables a complete, non-degraded analysis of the quantum states deemedinteresting at any moment in the simulation.

Preferably, the method comprises:

-   -   a step of communicating quantum states of one or more quantum        state vectors between a simulator in which those quantum states        are stored and an application terminal in which those quantum        states will be analyzed,    -   as those quantum states are communicated in multiple        installments, with the quantity of data communicated in each one        not exceeding the size of a buffer memory, that buffer memory        size being less than the size of the memory storing those        quantum states in the simulator, preferably at least 10 times        smaller, and preferentially at least 100 times smaller.

This enables a very sizable memory gain, especially in the applicationterminal, whose memory may be fairly limited.

Preferably, the size of the buffer memory, in the application terminaland in the simulator, is large enough for the time taken to process thecontents of that buffer memory by the application terminal to be longerthan the time taken to transfer the data communicated between thesimulator and the application terminal.

This sizable memory gain does not or almost does not come at the cost ofany slowdown in processing the data within the application terminal.

Preferably, the size of the buffer memory is between 1 MB and 100 MB,and very preferably between 3 MB and 20 MB.

The memory range is thereby optimized for a compromise between memorygain and preserving processing speed.

Preferably, the step of analysis is followed by a step of debugging theexecution of the quantum circuit.

This therefore enables a beneficial application of the analysis step,improving the quality and efficiency of the analyzed quantum circuit.

Preferably, the method comprises, between the post-selection step andthe analysis step:

-   -   a step of threshold filtration, setting a probability threshold        below which the corresponding quantum states are removed from        the quantum state vector to which they belong, and/or    -   a step of value filtration, selecting a value of a quantum state        for which the corresponding quantum states are kept in the        quantum state vector.

Multiple filtration steps may therefore be performed on the quantumstate vector. The filtering of the quantum states of the quantum statevector based on the various parameters makes it possible to furtherincrease the completeness of the analysis, by focusing on the quantumstates deemed interesting. The various types of filtration may becombined and/or stacked with one another.

Preferably, the method comprises, after the setting filtration step:

-   -   a step of renormalizing the quantum state vector, so that the        sum of the probabilities of the quantum states kept in that        quantum state vector is still equal to 1.

The step of renormalizing advantageously makes it possible to have acoherent filtered quantum state vector, particularly when quantum statesof the quantum state vector were removed from the quantum state vectorduring the filtration steps.

Preferably, the method is integrated into an application programminginterface (API) capable of accessing a server including a quantumcircuit execution simulator and a module for communicating with a remoteapplication terminal separate from the simulator.

This makes it possible to improve ease of use for a user-analyst fromtheir application terminal.

Preferably, the number of qubits in the quantum circuit is between 2 and1000, preferably between 10 and 50.

The analysis method of the invention operates even with large quantumcircuits, or with very large ones.

Preferably, the analysis method is implemented in python language. Thelanguage python is well-suited to this type of method for analyzing theoperation of a quantum circuit.

The invention and variants thereof may generally make it possible tooffer a method for analyzing a simulation of the execution of a quantumcircuit, enabling a complete and simplified analysis, particularly fordebugging the execution of the quantum circuit, and in particular foroffering a better compromise between on the one hand the simplificationof the analysis of the execution of a quantum circuit and on the otherhand the completeness of the analysis performed.

Such a solution makes it possible to solve the problems posed by knownsolutions.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features, details, and benefits of the invention will becomeapparent upon reading the detailed description below and upon analyzingthe attached drawings, in which:

FIG. 1

FIG. 1 shows a system making it possible to implement a method foranalyzing a simulation of the execution of a quantum circuit accordingto one embodiment of the invention;

FIG. 2

FIG. 2 shows a flowchart illustrating the main steps of the method foranalyzing a simulation of the execution of a quantum circuit accordingto one embodiment of the invention;

FIG. 3

FIG. 3 shows an example flow of the execution on a quantum state vectoraccording to one example embodiment.

DESCRIPTION OF THE EMBODIMENTS

Reference is now made to FIG. 1, in which an example system 1 making itpossible to implement a method for analyzing the execution of asimulation of a quantum circuit is illustrated.

The system 1 particularly comprises a simulator 2 of a quantum circuit.More specifically, the simulator 2 makes it possible to simulate aquantum processor.

As an output of the simulator 2, a quantum state vector is obtained. Thequantum state vector comprises 2^(n) quantum states, n being the numberof qubits that the simulation relies upon.

For example, the quantum state vector comprises between 2² and 2¹⁰⁰⁰. Inother words, the quantum circuit comprises between 2 and 1000 qubits.Preferably, the quantum state vector comprises for example between 2¹⁰and 2⁵⁰. In other words, the quantum circuit comprises between 10 and 50qubits.

The simulator 2 comprises for example a memory 3. The memory 3 mayparticularly be able to store the quantum state vector obtained. Thememory 3 therefore comprises a large storage capacity in order to beable to store a quantum state vector comprising between 2² and 2¹⁰⁰⁰ andpreferably between 2¹⁰ and 2⁵⁰ possible quantum states.

The simulator 2 is for example stored on a server 4.

The server 4 comprises for example a communication module 5 a, making itpossible to enter into communication with an application terminal 6 viaa communication module 5 b of the application terminal 6.

The application terminal 6 is for example remote from the server 4. Theapplication terminal 6 particularly enables an analyst to access thequantum state vector in order to analyze it, without storing it.

To that end, an iterator 7 may be implemented within the system 1. Theiterator 7 enables an interaction between the application terminal 6 andthe simulator 2.

More specifically, the iterator 7 makes it possible to avoid duplicatingall the information, in other words, the quantum state vector obtainedat the output of the simulator 2, to the application terminal 6. Inother words, the iterator 7 enables the retrieval of the information atthe output of the simulator 2, on the application terminal 6. Theiterator 7 therefore enables an analyst to access the information at theoutput of the simulator 2 in a simple way.

More specifically, the iterator 7 loops onto each quantum state of thequantum state vector obtained at the output of the simulator 2, so thateach quantum state can be retrieved on the application terminal.

The iterator 7 may further comprise filters F1, F2, and F3 to be appliedto the quantum state vector. Those filters are described in greaterdetail with reference to FIG. 2.

Furthermore, the system 1 may comprise a buffer memory 8 a implementedin the simulator 2, and a buffer memory 8 b implemented in theapplication terminal 6.

The information obtained at the output of the simulator 2 is for exampletransmitted to the application terminal 6, by means of the iterator 7,via the buffer memories 8 a, 8 b.

The iterator 7 is stored in the simulator 2 and is in communication withthe buffer memory 8 a.

The use of buffer memories 8 a, 8 b makes it possible to greatly reducethe memory size needed to access the information obtained at the outputof the simulator 2.

The size of the buffer memories 8 a, 8 b may be chosen so that the timetaken to process the content of the buffer memory 8 b by the applicationterminal 6 is greater than the time taken to transfer the informationobtained at the output of the simulator 2 to the application terminal 6.

Thus, the size of the buffer memories 8 a, 8 b may be chosen to be 1 MBand 100 MB, and preferably between 3 MB and 20 MB.

The result is that the size of the buffer memories 8 a, 8 b is at least10 times, and preferably at least 100 times smaller than the memory 3storing the information obtained at the output of the simulator 2.

Thus, at the end of the simulation, a quantum state vector 2^(n) isobtained. The quantum state vector 2^(n) is stored in the memory 3 ofthe simulator 2. The memory 3 communicates with the iterator 7. Morespecifically, the memory 3 transmits sections of the quantum statevector 2^(n) to the iterator 7. The iterator 7 is configured to processthose sections of the quantum state vector 2^(n), particularly by meansof the filters F1, F2, and F3. The iterator 7 is configured to send thesections of the quantum state vector to the buffer memory 8 a of thesimulator 2 which transmits them, via the communication interfaces 5 a,5 b, to the application terminal 6. The buffer memory 8 b of theapplication terminal 6 receives the sections of the quantum statevector, so that they can be analyzed by an analyst directly on theapplication terminal. Communication between the server 4 and theapplication terminal 6 is for example done by radio waves or over theInternet.

According to one embodiment variant, the iterator 7 is stored within thebuffer memory 8 a of the simulator 2.

FIG. 2 depicts the main steps of a method for simulating the executionof a quantum circuit according to one example embodiment.

During the step of simulation S1, the simulation of the quantum circuitis launched. When simulating the execution of a quantum circuit, thequantum state vector obtained is made up of a plurality of qubits havinga quantum state 0 and 1.

With reference to FIG. 3, the quantum states of the qubits of thequantum state vector are not known. A probability is associated witheach quantum state of a qubit, with the sum of the probabilities beingequal to 1.

Thus, when the qubit 2 is measured, a probability p is associated withone of the two quantum states 0 or 1, and a probability p−1 isassociated with the other quantum state 0 or 1.

With each measurement, a new probability is associated with each quantumstate 0 or 1 of the measured qubits.

Thus, when the qubit n is measured, a probability p is associated withone of the two quantum states 0 or 1 for the first qubit, and aprobability 1-p is associated with the other one of the two quantumstates 0 or 1. Likewise, for the nth qubit, a probability p isassociated with one of the two quantum states 0 or 1 of the nth qubit,and a probability 1-p is associated with the other one of the twoquantum states 0 or 1 of the nth qubit.

The probabilities p, p and p are generally different, but may, in somecases, be equal.

During the simulation, intermediate measurements are taken for eachqubit. Those intermediate measurements influence the quantum state ofthe measured qubits, leading to a qubit to be set to a quantum statebetween 0 and 1.

The simulation therefore makes it possible to obtain an execution tree,illustrated in FIG. 3, in which the nodes represent each qubit of thequantum state vector. Following the intermediate measurements taken onthe qubits, two branches depart from each node: each branch representinga quantum state of the measured qubit with which its probability isassociated.

At the end of the execution, a plurality of quantum state vectors,comprising 2^(n) quantum states, is obtained.

The triangles symbolize quantum operations that can be carried out onqubits. By quantum operations it is meant for example applying quantumgates to the qubits, which may or may not modify the values of thequbits.

In the post-selection step S2, one or more particular values of one ormore qubits are post-selected at one or more steps of the simulation.Particular value means a particular quantum state.

In other words, it is possible to post-select one or more branches ofthe execution. More specifically, it is possible to post-select aquantum state from one or more qubits at the time of execution.

Post-selection may amount to choosing the values of the quantum statesof the quantum state vector.

For a given simulation, the post-selections of values of qubits may besuccessive. The post-selections may also be repetitive. For example, itis possible to post-select the same qubit value several times. Forexample, it is possible to post-select different values for the samequbit several times. For example, it is possible to select differentvalues of different qubits several times.

In the remainder of the description, the term post-selection is used,although multiple post-selections may be performed, as described above.

Post-selection is performed at multiple steps of the simulation. Forexample, post-selection is performed at the output of the measurement ofthe qubits.

Post-selection is performed following a quantum gate operation on thequbit.

Next, a setting filtration step S3 is carried out. The settingfiltration step sets the value of one or more quantum states of thequantum state vector(s) derived from post-selection(s) of qubits.

The terms quantum state vector derived from post-selection(s) of qubitsand quantum state vector of the post-selected qubit(s) are usedinterchangeably in the remainder of the description.

The setting filtration step S3 is for example performed by the iterator7, and particularly by applying the filter F1 depicted in FIG. 1.

The setting filtration step S3 is for example located between the stepof post-selection S2 and the step of retrieval S5, described below.

The setting filtration step S3 particularly comprises the setting ofquantum state values of the quantum state vector derived frompost-selection.

The setting filtration step particularly enables the iterator 7 to notneed to browse the entire quantum state vector derived frompost-selection of qubits when it is retrieved on the applicationterminal 6.

More specifically, if, out of one quantum state vector derived frompost-selection of qubits of n quantum states, three quantum states areset during the setting filtration step, a vector of size 2^(n-3) isretrieved by means of the iterator 7, rather than a quantum vector ofsize 2^(n) as before.

The setting filtration step therefore further makes it possible toreduce the size of the information to be transmitted to the applicationterminal.

According to one embodiment, an additional filtration step S4 isperformed.

The additional filtration step S4 is implemented by the iterator 7.

For example, the additional filtration step S4 may comprise thresholdfiltration and/or value filtration of the quantum states of the quantumstate vector derived from the post-selection of qubits.

Threshold filtration particularly comprises the defining of aprobability threshold for which the quantum states associated with aprobability that fall below that threshold are not retained.

Threshold filtration is performed by applying the filter F2 illustratedin FIG. 1.

Value filtration particularly comprises the defining of a quantum statevalue for which the quantum states of the quantum state vector derivedfrom post-selection of qubits having that value are not retrieved.

Value filtration is performed by applying the filter F3 illustrated inFIG. 1.

This additional step of filtration S4 makes it possible, on the onehand, to reduce the size of the information to be sent to theapplication terminal 6 by eliminating certain quantum states of thequantum state vector derived from post-selecting qubits, and, on theother hand, to increase the completeness of the analysis by focusingonly on the quantum states deemed interesting.

The filtration types may be combined and/or stacked for multiple quantumstates of the quantum state vector.

According to one embodiment, the steps of setting filtration S3 andadditional filtration S4 may be followed by a step of renormalizing thefiltered quantum state vector, during which the probability of eachquantum state saved in the filtered quantum state vector is modified sothat the sum of the probabilities of each quantum state is equal to 1.

Next, a step of retrieval S5, by the iterator 7, of all or some of thequantum states of the quantum state vector(s) derived from thepost-selections of qubits and filtered is carried out.

The step of retrieval S5 may also comprise the retrieval, by theiterator 7, of all or some of the quantum states of the quantum statevector(s) derived from the post-selection of qubits and derived fromdifferent types of filtration, described with reference to the steps ofsetting filtration S3 and additional filtration S4.

The step of retrieval S5 may further comprise the retrieval of each ofthe probabilities associated with each quantum state of the retrievedquantum state vector, whether renormalized or not.

In particular, the iterator 7 is able to identify a parameterrepresentative of the probability of each quantum state of the quantumstate vector, between the step of post-selection and the step ofretrieval, for example before the step of setting filtration.

The iterator 7 is for example able to read the quantum state vector, andto associate a probability with each quantum state. The iterator isfurther able, based on a complex model of the matrix stabilizer type, torecalculate the elements of the matrix in order to put them into theform of a readable quantum state vector and to associate a probabilitywith each quantum state of that quantum state vector.

The iterator 7 is configured to iterate on each of the quantum states ofthe quantum state vector obtained after step S4, and potentially on theprobabilities associated with them, so that an analyst can access itfrom the application terminal 6 for a step of analysis S6.

The step of analysis S6 comprises for example the comparison of thequantum states of the quantum state vector retrieved with the quantumstates of the quantum state vector expected following the steps ofpost-selection S2 and setting filtration S3.

In the step of debugging S7, the data from the analysis may be used forthe purposes of debugging the execution of the quantum circuit.

The method is implemented on an application programming interface (orAPI) that can access the server 4.

In one variant, the threshold filtration particularly comprises thedefining of a probability threshold for which the quantum statesassociated with a probability that fall above that threshold are notretained.

In one variant, the value filtration particularly comprises the definingof a quantum state value for which only the quantum states of thequantum state vector derived from post-selection of qubits having thatvalue are retrieved.

INDUSTRIAL APPLICATION

The invention may have application particularly in the field of quantumcomputing and debugging the execution of quantum circuits.

The invention is not limited to the examples described above, which areonly given as examples, but rather encompasses all variants that aperson skilled in the art may envision within the scope of theprotection sought.

LIST OF REFERENCE SIGNS

-   -   1: System    -   2: quantum simulator    -   3: memory    -   4: server    -   5: communication interface    -   6: application terminal    -   7: iterator    -   8 a, 8 b: buffer memories    -   S1: step of simulation    -   S2: step of post-selection    -   S3: step of setting filtration    -   S4: step of additional filtration    -   S5: step of retrieval    -   S6: step of analysis    -   S7: step of debugging

1. Method for analyzing a simulation of the execution of a quantumcircuit, comprising: a step of post-selecting (S2) one or moreparticular values of one or more qubits at one or more steps of thesimulation, a step of retrieving (S5), by an iterator (7), all or someof the quantum states of the quantum state vector(s) derived from thepost-selection(s) of qubits, a step of analyzing (S6) the part of saidsimulation that corresponds to the post-selection(s) of qubits and tothe quantum state vector(s) retrieved.
 2. Method for analyzing asimulation of the execution of a quantum circuit according to thepreceding claim, characterized in that it comprises, between the step ofpost-selection (S2) and the step of analysis (S6): a step of settingfiltration (S3) that sets the value of one or more quantum states of thequantum state vector(s) derived from the post-selections of qubits. 3.Method for analyzing a simulation of the execution of a quantum circuitaccording to the preceding claim, characterized in that it comprises,between the step of post-selection (S2) and the step of analysis (S6),and before the step of retrieval (S5): the step of setting filtration(S3) that sets the value of one or more quantum states of the quantumstate vector(s) derived from the post-selection(s) of qubits.
 4. Methodfor analyzing a simulation of the execution of a quantum circuitaccording to any one of the claims 1 to 3, characterized in that itcomprises: a step of identifying each quantum state of said quantumstate vector(s) and a parameter representative of a probability that isrespectively associated with said each quantum state, located betweenthe step of post-selection (S2) and the step of retrieval (S5), the stepof retrieval (S5) further comprising the retrieval of each parameterrepresentative of the probability respectively associated with eachquantum state.
 5. Method for analyzing a simulation of the execution ofa quantum circuit according to any one of the preceding claims, whereinthe step of post-selecting (S2) one or more particular values of one ormore qubits is carried out at the output of the measurement of saidqubit(s).
 6. Method for analyzing a simulation of the execution of aquantum circuit according to any one of the preceding claims, whereinthe step of post-selecting (S2) one or more particular values of one ormore qubits is carried out after a quantum gate operation on saidqubit(s).
 7. Method for analyzing a simulation of the execution of aquantum circuit according to any one of the preceding claims,characterized in that it comprises: a step of communicating quantumstates of one or more quantum state vectors between on the one hand asimulator (2) in which those quantum states are stored and on the otherhand an application terminal (6) wherein those quantum states will beanalyzed, as those quantum states are communicated in multipleinstallments, with the quantity of data communicated in each one notexceeding the size of a buffer memory (8 a, 8 b), that buffer memory (8a, 8 b) size being less than the size of the memory (3) storing thosequantum states in the simulator (2), preferably at least 10 timessmaller, and preferentially at least 100 times smaller.
 8. Method foranalyzing a simulation of the execution of a quantum circuit accordingto claim 7, characterized in that: the size of the buffer memory (8 a, 8b), in the application terminal (6) and in the simulator (2) is largeenough for the time taken to process the contents of that buffer memory(8 a, 8 b) by the application terminal (6) to be longer than the timetaken to transfer the data communicated between the simulator (2) andthe application terminal (6).
 9. Method for analyzing a simulation ofthe execution of a quantum circuit according to one of the claims 7 to8, characterized in that: the size of the buffer memory is between 1 MBand 100 MB, preferably between 3 MB and 20 MB.
 10. Method for analyzinga simulation of the execution of a quantum circuit according to any oneof the preceding claims, characterized in that: the step of analysis(S6) is followed by a step of debugging (S7) the execution of thequantum circuit.
 11. Method for analyzing a simulation of the executionof a quantum circuit according to any one of the preceding claims,characterized in that it comprises, between the step of post-selection(S2) and the step of analysis (S6): a step of threshold filtration (S4),setting a probability threshold below which the corresponding quantumstates are removed from the quantum state vector to which they belong,and/or a step of value filtration (S4), selecting a value of a quantumstate for which the corresponding quantum states are kept in the quantumstate vector.
 12. Method for analyzing a simulation of the execution ofa quantum circuit according to any one of claim 2, 3, or 11,characterized in that it comprises, following the step of settingfiltration (S3): a step of renormalizing the quantum state vector, sothat the sum of the probabilities of the quantum states kept in thatquantum state vector is still equal to
 1. 13. Method for analyzing asimulation of the execution of a quantum circuit according to any one ofthe preceding claims, characterized in that it: is integrated into anapplication programming interface (API) capable of accessing a server(4) including a quantum circuit execution simulator (2) and a module (5)for communicating with a remote application terminal (6) separate fromthe simulator (2).
 14. Method for analyzing a simulation of theexecution of a quantum circuit according to any one of the precedingclaims, characterized in that: the number of qubits in the quantumcircuit is between 2 and 1000, preferably between 10 and
 50. 15. Methodfor analyzing a simulation of the execution of a quantum circuit,comprising: a step of post-selecting (S2) one or more particular valuesonce the measurement of one or more qubits is output, a step ofanalyzing (S6) the part of said simulation that corresponds to thepost-selection(s) of qubits.